1. Field of the Invention
The present invention relates to an illumination control apparatus and, more particularly, to an illumination control apparatus responsive to illumination loads having different dimming characteristics.
2. Description of the Related Art
As a conventional illumination control apparatus used in a general office building or the like, a control apparatus for performing illumination control with the same dimming characteristics is known even if, for example, a lighting unit with a louver and a lighting unit without a louver, or a lighting unit having high-output characteristics and a lighting unit having a normal output characteristics are used together. For this reason, if lighting units having different light output characteristics are used together, their brightness and dimming characteristics differ from each other. In this specification, a dimming characteristic means a degree of change of an optical output value obtained when a power supplied to an illumination load is changed from zero to a rated value.
In order to set uniform brightness among lighting units having different output characteristics, the present inventors have developed an illumination control apparatus constituted by a plurality of circuits having different dimming characteristics in correspondence with the different output characteristics. This illumination control apparatus is designed to select circuits corresponding to the types of illumination loads and selectively connect the circuits to the loads through selection jumpers, thus setting dimming characteristics corresponding to the types of illumination loads.
If, however, the currently used illumination loads are replaced with illumination loads having different dimming characteristics, or louvers are attached or detached to or from the currently used illumination loads with a change in interior layout or the like, the overall control apparatus or its dimming characteristics must be changed. This requires a cumbersome operation.
In a system in which illumination loads connected to a dimming terminal controlled by a main operation panel is subjected to dimming control by means of a dimming level setter such as a hand dimming switch, dimming control of each illumination load is performed in proportion to dimming data corresponding to an operation amount of the dimming level setter fetched by the dimming terminal.
According to human visual sensitivity, in a dark place, a slight change in brightness is felt as a large change in brightness. In contrast to this, in a bright place, a slight change in brightness is not felt much.
If, therefore, dimming control of each illumination load is performed in proportion to an operation amount of a dimming level setter, as in the above-mentioned illumination control apparatus, the level setter must be finely operated to obtain dimming control adapted to human visual sensitivity to brightness. This also poses problems in terms of operability.